chapter 7.  ELEMENTS OF GROUPS 16, 17 AND 18 class 12 chemistry textbook solution

Answer:-

The acidic character of hydrides of group 16 elements (oxygen, sulfur, selenium, tellurium) increases from H2O to H2Te due to the following factors:

1. Size of the central atom: As you move down the group from oxygen (O) to tellurium (Te), the size of the central atom increases. This increase in atomic size is due to the addition of more electron shells as you move down the group. As a result, the valence electrons in the outermost shell are farther from the nucleus. This increase in size leads to a weaker attraction between the central atom and the hydrogen atom in the hydride molecule.

2. Bond strength: The strength of the bond between the central atom and hydrogen atom decreases as you move from H2O to H2Te. This is because the central atom becomes larger and the bond between the larger central atom and hydrogen atom becomes weaker. In other words, the bond in H2Te is weaker than the bond in H2Se, which is weaker than the bond in H2S, and so on.

3. Polarizability: As the central atom gets larger, it becomes more polarizable. Polarizability is the ability of an atom or ion to distort the electron cloud of its neighboring atoms or ions. In larger atoms like tellurium, the electrons are further from the nucleus and are more easily distorted by the presence of other charged species. This increased polarizability makes it easier for tellurium in H2Te to attract the shared electrons towards itself, making it more acidic.

4. Bond strength and acidity: The weaker the bond between the central atom and hydrogen atom, the easier it is for the central atom to release a hydrogen ion (H+). In other words, weaker bonds are associated with stronger acidity. Since the bond strength decreases as you move down the group, hydrides with larger central atoms, such as H2Te, are more likely to release H+ ions in solution, making them more acidic.

In summary, the increasing size of the central atom, the weakening of the central atom-hydrogen bond, the increased polarizability, and the tendency to release H+ ions in solution all contribute to the increasing acidic character of hydrides from H2O to H2Te within Group 16 of the periodic table.